Measurement of myelin basic protein and of anti-basic protein antibodies by ELISA utilizing biotinylated antibodies.

Immunoglobulins were conjugated to peroxidase by the biotin-avidin method and used in ELISA systems for measuring myelin basic protein (MBP) and anti-MBP antibodies. To measure concentration of MBP, microplate wells were coated with affinity purified rabbit anti-MBP antibodies and incubated with varying concentrations of MBP. Bound antigen was measured by incubating with biotinylated anti-MBP antibodies and avidin-peroxidase. As little as 0.2 ng/ml of MBP could be measured by this assay. To measure anti-MBP antibodies, microplate wells were coated with human MBP and incubated with varying concentrations of affinity purified rabbit anti-human MBP antibodies. Binding was measured by incubating with either peroxidase-conjugated anti-rabbit antibodies or biotinylated anti-rabbit antibodies and avidin peroxidase. The two methods were equally sensitive. The avidin-biotin method for enzyme conjugation promises to be a useful and versatile tool for ELISA systems.